Locking fastener



nired Sie@ PefefffO- 3,012,807 Y f f LOCKING FASTENER Winthrop F.

United-Carr Fastener Corporation, Cambridge, Mass., a corporation of Deiaware Y Filed Dec. '7, 1959Ser. No. 857,792

2 Claims. (Cl. 292-321) This invention relates to a tamperproof locking fastener and more particularly to fasteners used to close containers where it is necessary to easily discover if Vthe fastener has been opened.

It is an object of this invention to provide a fastener which presents external surfaces, after engagement, which will prevent an instrument from. opening the fastener.

It is a further object of the invention to provide a fastener having a camming surface and tab with a means for locking the tab with the camming-surface.

Other objects of the invention will, in part, be obvious, and will, in part appear hereinafter.

In the drawing:

FIG. l is a top plan view of the fastener;

FIG. 2 is a front side elevation of the fastener shown in FIG. l;

FG. 3 is a back side elevation of the fastener shown in FIG. 1;

FIG. 4 is a section taken on line 4-4 of FIG. 2;

FIG. 5 is a section taken on line 5 5 of FIG. 2;

FIG. 6 is a section of the fastener engaged; and

FIG. 7 is a View of the fastener engaged to a hasp and staple.

One form of the fastener is illustrated in FIGS. 1 through 7. The fastener comprises a male element 2, female element 4 and a connecting strip 6 which connects the male 2 and female 4 elements as best shown in FIG. l. The male element 2 comprises a base portion 8 in the form of a rectangle having a pair of terminal ends and 12. A rear wall portion 14, substantially rectangular in shape, is formed at the terminal end 10 in integral right angle relationship with the said base 8. Two side walls 16 are formed in integral right angle relationship with said base 8 and in spaced parallel relationship with each other to form a four-sided compartment with said base 8 and said rear wall portion 14. The said side walls 16 do not run the full length of the base 8 but terminate at a predetermined point between the terminal ends 10 and 12 of the base 8 as illustrated in FIG. 3. A tab 18 is formed at a point intermediate and slightly in front of the free ends of the side walls 16 in integral normal relationship with the said base 8. The engaging end of the tab 18 lies slightly inside the area between the side walls 16 although the said engaging end 20 may be placed slightly in front of the said compartment. ln the particular embodiment shown, the tab 18 is rectangular in form, and the angle of inclination as shown in FIG. 6 is toward the plane of the rear wall portion 14. The tab 18 is constructed to provide some spring action against horizontal forces. The rectangular form of the tab 18 is not mandatory and an arcuate shape would also suiiice. A guide 22 is formed integral with the terminal end 12 of the base 8 in spaced parallel relationship with the rear wall portion i4 having a length equal to the inside distance between the side walls 16. The height of the guide 22 from the plane of the base portion 8 is less than the height of the tab 18 taken from the same plane. In the illustrated embodiment, the yguide 22 is in the form of a rectilinear parallelepiped although other forms may be used, such as a plain parallelepiped.

The female element 4 comprises a pair of covering side walls 24 connected at one of their terminal ends by a back wall 26. rlfhe covering Side walls 24 are in spaced parallel relationship and in integral right angle relation- Ashworth, Wenham, Mass., assigner tov 4italiennes Dec. 12, 1961 ship withsaid back wall 26. A stop 28 is set approximately midway of the length of one of the covering side mentioned stop 28.

edge 3:2 of the platform 30 is in spaced parallel relationship with` the back wall 26. The forward edge 34 of the' platform 38 lies on the same plane as the edges of said' covering side walls 24. The platform 30 takes the foririV of a substantially broad rectangular parallelepiped extending from the rear edges of the stops 28 to the forward redges of the covering side walls 24, as best shown' in FIG. 2, with the exception of the rectangular notches 36 formed in the platform 30 as shown in FIG. 3. In the area formed between the stops 28 and extending to the forward edge of the platform 30, a camming portion or protuberance 38 is formed and any suitable shape may be utilized, one of whose surfaces is called herein the camming surface 46, and which may be arcuate in form.

Along the line of the camming surface 40, directly in front l of the stops 28, a V slot 42 is formed to engage the tab 18 when the male element 2 is placed into the female element 4, said camming portion 38 has a height at its highest point less than the height of said stops 28. A pair of cubical projections 44 are formed extending into the area between the covering side walls 24 in spaced parallel relationship with each other as shown in FIG. l, said cubical projections 44 having an area substantially equal to the area of the said notches 36. A rectangular shield 46 is formed connecting the covering side walls 24 and the back wall 26 in integral right angle relationship therewith. Said shield 46 extends from the back wall 26 to the plane formed by the rearward portions of the stops 28 and the rear edge 32 of the platform 38.

The connecting strip 6 is integral with and connects the male element 2 and the female element 4 as shown in FIGS. l, 2 and 3. This connection is made to face the locking guide 22 and the tab 18 toward an extension of the plane of the platform 38 and the rear wall portion 14 of the male element 2 rests on an extension of the plane of the back wall 26 of the female element 4. The connecting strip 6 is made of a flexible material such as plastic, fabric or the softer metals. In order to increase the flexibility of a plastic connecting strip, the center portion may be dished out as illustrated in FIGS. 2 and 3.

To engage the male element 2 with the female element 4 around a hasp 48 and staple 50, vthe hasp 48 is dropped on the staple 50 in the usual manner. The connecting strip 6 is passed around one leg of the staple 50 over the hasp 48 as illustrated in FIG. 7. The base portion 8 of the male element 2 is passed between the covering side walls 24 of the female element 4, and under the cubical projections 44 of the female element 4. As the male element 2 is passed between the said covering side walls 24, the locking guide 22 passes between the stops 28 and the tab 18 slides over the camming surface 40 of the camming portion 38 coupled with the movement of the male element 2, the female element 4 is so constructed that the cubical projections 44 in combination with the camming surface 48 create horizontal forces on the tab 18 exing it toward the rear wall portion 14 of the male element 2. As the rnale element 2 continues to pass into the female element 4, the tab 18 snaps into the V slot 42 in the camming surface 40 at the Sametime the rear wall portion 14 abuts the forward edge 34 of the platform 30. The base portion 8 has by this time passed beneath the shield 46 and remains in abutting relationship therewith after en- Q gagement of the tab `18 with the V slot 42. The shield 46 prevents the terminal end 12 of the base portion 8 from tilting away from the camming surface 40 and thus preventing engagement of the tab 18 and the V slot 42.

I claim:

1. A plastic locking fastener comprising a connecting strip integral with a one piece molded male element and a one piece molded female element, said male element having a base portion, wall portions'and a single llexible tab in right angle relationship with said base portion and said female element having wall enclosing portions and a cam portion with a slot formed therein, said tab having a length greater than the depth of said slot.

2. A locking fastener comprising a male element and a female element, said male element having a base portion in integral right angle relationship with a rear wall portion, said rear wall portion in right angle relationship With a pair of side walls which are in spaced relation with each other and in integral right angle relationship with said base portion, said side walls terminating less than 20 the length of said base portion, a single ilexible tab in normal angular relationship with said base portion protruding in front of the area formed by said side walls and a guide in right angle relationship with the opposite end of said base portion from said rear wall portion and said female element having a platform, two covering side walls in angular relationship with said platform and in spaced parallel relationship with each other, a back wall in spaced relation to said platform and in right angle relationship with said covering side walls, a camming portion integral with said platform and protruding into the area between said covering side Walls, said camming portion having a slot for engaging the tab of said male element.

References Cited in the le of this patent UNITED STATES PATENTS 312,963 Brooks Feb. 24, 1885 998,878 Dinsmoor July Z5, 1911 2,809,065 Erke Oct. 8, 1957 FOREIGN PATENTS 11,644 Great Britain A D. 1909 

